Network slicing awareness in IP multimedia subsystem

Abstract

A method performed within a communication system comprising a 5G core network and an IP Multimedia Subsystem (IMS) network, where the 5G core network is configured to implement a plurality of virtual core network slices each having a slice identifier. The method comprises assigning one of said virtual core network slices to a User Equipment (UE) at or following registration of said UE with the IMS network, and sending from the UE or the 5G core network, to the IMS network, the slice identifier of the network slice assigned to the UE. The method further comprises receiving the slice identifier within the IMS network and storing in the IMS network a mapping between the UE and the received network slice identifier. The slice identifier is used within the IMS network to provision services to the UE.

The invention claimed is: 
     
       1. A method performed within a communication system comprising a 5G core network and an IP Multimedia Subsystem (IMS) network, where the 5G core network is configured to implement a plurality of virtual core network slices each having a slice identifier, the method comprising:
 assigning one of said virtual core network slices to a User Equipment (UE) at or following registration of said UE with the IMS network; 
 sending from the 5G core network, to the IMS network, the slice identifier of the network slice assigned to the UE; 
 receiving the slice identifier within the IMS network; 
 storing in the IMS network a mapping between the UE and the received network slice identifier; and 
 using the slice identifier within the IMS network to provision services to the UE. 
 
     
     
       2. The method according to  claim 1 , wherein said using the slice identifier to provision services comprises providing a service from a subset of services identified as being available to the UE based on the slice identifier. 
     
     
       3. The method according to  claim 1  further comprising sending UE charging data from the IMS network to a remote billing system, wherein said charging data includes the slice identifier of the network slice assigned to the UE. 
     
     
       4. The method according to  claim 1  further comprising performing the method for a plurality of UEs and storing in the IMS network a mapping between the plurality of UEs registered with the IMS and respective slice identifiers. 
     
     
       5. The method according to  claim 4  further comprising gathering, within the IMS network, network data from the plurality of UEs and using the mapping to generate network slice specific data from said network data. 
     
     
       6. The method according to  claim 5 , wherein said network data comprises a call drop rate, a call success rate, or both the call drop rate and the call success rate of the plurality of UEs, and said network slice specific data accordingly comprises the call drop rate, the call success rate, or both the call drop rate and the call success rate of each network slice assigned to one or more of the UEs. 
     
     
       7. The method according to  claim 1 , wherein said sending comprises sending the slice identifier from a Policy Control Function (PCF) or a Policy and Charging Rules Function (PCRF) of the 5G core network. 
     
     
       8. The method according to  claim 7 , wherein said sending is performed in response to receiving at the PCF or PCRF of the 5G network a policy request from a Proxy-Call Session Control Function (P-CSCF) of the IMS network, wherein said policy request is for a session associated with the UE. 
     
     
       9. A method performed by a Policy Control Function (PCF) or a Policy and Charging Rules Function (PCRF) of a 5G core network within a communication system comprising the 5G core network and an IP Multimedia Subsystem (IMS) network, where the 5G core network is configured to provide a plurality of virtual core network slices each having a slice identifier, the method comprising:
 receiving from a Proxy-Call Session Control Function (P-CSCF) of the IMS a policy request for a session associated with a User Equipment (UE); 
 determining policy rules for the session; 
 sending a request to a Session Management Function (SMF) of the 5G core network to implement the policy rules; 
 receiving from the SMF a response including a slice identifier of a network slice assigned to the UE; and 
 sending the response with the slice identifier to the P-CSCF of the IMS. 
 
     
     
       10. The method according to  claim 9 , wherein the policy request received from the P-CSCF and the response sent to the P-CSCF are RESTful Hyper Text Transmission Protocol (HTTP) messages or DIAMETER protocol messages. 
     
     
       11. The method according to  claim 9 , wherein the request sent to the SMF and the response received from the SMF are RESTful Hyper Text Transmission Protocol (HTTP) messages. 
     
     
       12. A method performed by a Proxy-Call Session Control Function (P-CSCF) of an IP Multimedia Subsystem (IMS) network within a communication system comprising a 5G core network and the IMS network, where the 5G core network is configured to provide a plurality of virtual core network slices each having a slice identifier, the method comprising:
 sending a policy request for a session associated with a User Equipment (UE) to a Policy Control Function (PCF) or a Policy and Charging Rules Function (PCRF) of the 5G core network; and 
 receiving a response from the PCF or PCRF including a slice identifier of a network slice assigned to the UE. 
 
     
     
       13. The method according to  claim 12  further comprising the P-CSCF adding the network slice identifier as an asserted network slice feature tag. 
     
     
       14. The method according to  claim 13 , wherein the asserted network slice feature tag replaces a network slice feature tag previously provided by the UE. 
     
     
       15. An apparatus for implementing a Policy Control Function (PCF) or a Policy and Charging Rules Function (PCRF) of a 5G core network within a communication system comprising the 5G core network and an IP Multimedia Subsystem (IMS) network, where the 5G core network is configured to provide a plurality of virtual core network slices each having a slice identifier, the apparatus comprising:
 a receiver configured to receive from a Proxy-Call Session Control Function (P-CSCF) of the IMS a policy request for a session associated with a User Equipment (UE); 
 a processor configured to determine policy rules for the session; and 
 a sender configured to send a request to a Session Management Function (SMF) of the 5G core network to implement the policy rules, 
 wherein the receiver is further configured to receive from the SMF a response including a slice identifier of a network slice assigned to the UE, and the sender is further configured to send the response with the slice identifier to the P-CSCF of the IMS. 
 
     
     
       16. An apparatus for implementing a Proxy-Call Session Control Function (P-CSCF) of an IP Multimedia Subsystem (IMS) network within a communication system comprising a 5G core network and the IMS network, where the 5G core network is configured to provide a plurality of virtual core network slices each having a slice identifier, the apparatus comprising:
 a sender for sending a policy request for a session associated with a User Equipment (UE) to a Policy Control Function (PCF) or a Policy and Charging Rules Function (PCRF) of the 5G core network; and 
 a receiver for receiving a response from the PCF or PCRF including a slice identifier of a network slice assigned to the UE.